Sugars are of nutritional importance to both mono-gastric and ruminant animals. In recent years, researchers have been investigating sources for sugar, such as sugar-bearing industrial food processing by-products, fermentation by-products, or other by-products, for use in animal feed. In many cases, such sugar-bearing sources, such as cane molasses, have a high sugar content that can be used in animal feed formulations or supplements. Such sugar-bearing sources are usually liquids, and are easily handled by conventional mixing equipment in animal feed processing plants.
Small concentrations of carboxylic acids have traditionally been used as preservatives in animal feed products. Recent research efforts have indicated that, in sufficient concentrations, free formic acid is capable of providing equivalent performance benefits to those obtained from growth promoting antibiotics. See Peter Best and Clayton Gill, Formic Acid Plus Phytase For Pigs, FEED MANAGEMENT, August 1998, Volume 49, Number 8, pp. 23-24. For example, a concentration of about 6-8 kg of formic acid per metric ton of an animal feed of the complex European diet is recognized as providing such a benefit, which is about 0.13-0.17 equivalent of the formic acid per 1,000 g of animal feed. A concentration of about 8-10 kg of propionic acid per metric ton of animal feed is also expected to provide such a benefit, which is about 0.11-0.14 equivalent of the propionic acid per 1,000 g of animal feed. Somewhat lower dosages would be expected to be sufficient for a simpler maize-soya animal feed mixture of the type found in the United States.
Of course, to obtain a final animal feed product that has dosages of about 0.10 equivalent carboxylic acid per kilogram of the animal feed would be expected to require much higher concentrations of the carboxylic acid in a feed supplement or additive ingredient to be added the bulk feed mixture to obtain the animal feed product with the desired concentrations. For example, an animal feed supplement would typically be expected to be added to the bulk feed mixture (e.g., maize-soya) at the rate of about 2 weight percent up to about 10 weight percent.
Carboxylic acids are, of course, acidic by nature. Generally, the fewer carbon atoms in the carboxylic acid, the stronger the acidic property. Formic acid and other short-chain and cyclic carboxylic acids, that is, carboxylic acids having between 1 and 8 carbon atoms, are quite acidic. Longer-chain carboxylic acids, such as the C.sub.14 -C.sub.22 fatty acids, tend to be much less acidic. Adding carboxylic acid, particularly the carboxylic acids having between 1 and 8 carbon atoms, to an aqueous feed mixture in an amount effective to achieve the desired effect tends to substantially lower the pH of the resulting composition. This can be a problem because conventional animal feed processing equipment is not designed for handling liquids that have an acidic pH value of less than about 3.5.
It would be desirable to provide an animal feed ingredient that included both the sugar source and the nutritive and other benefits of carboxylic acid. Furthermore, it would be desirable to have such a sugar-bearing feed ingredient that could be handled in conventional animal feed processing equipment.